Liao Jie, Wang Xuanyu, Wang Yang, Su Songyang, Nairan Adeela, Kang Feiyu, Yang Cheng
Division of Energy and Environment, Graduate School at Shenzhen, Tsinghua University Shenzhen 518055 China
School of Materials Science and Engineering, Tsinghua University Beijing 100084 China.
RSC Adv. 2018 May 11;8(31):17263-17271. doi: 10.1039/c8ra02844c. eCollection 2018 May 9.
Hierarchical nanostructured electrodes with excellent electronic properties and high specific surface areas have promising applications in high-performance supercapacitors. However, high active mass loading and uniform structure are still crucial in fabricating such architectures. Herein, Co(OH) nanoflakes were homogeneously deposited on nickel nanowire arrays (NNA) through a hydrothermal approach to form an NNA@Co(OH) (NNACOH) composite electrode. The as-synthesized one dimensional (1D) system had a lavender-like structure with a high mass loading of 5.42 mg cm and a high specific surface area of 74.5 m g. Due to the unique electrode structure characteristics, the electrode could deliver a high specific capacitance of 891.2 F g at the current density of 1 A g (corresponding to an areal capacitance of 4.83 F cm at 5.42 mA cm). The capacitance could still maintain a high value of 721 F g when the current density is increased to 50 A g. In addition, the electrode showed superior cycle stability with a capacitance retention of 89.3% after charging/discharging at the current density of 10 A g for 20 000 cycles. A flexible asymmetric supercapacitor (ASC) was assembled by employing NNACOH as the positive electrode and activated carbon (AC) as the negative electrode. It delivered a maximum energy density of 23.1 W h kg at the power density of 712 W kg and an energy density of 13.5 W h kg at the maximum power density of 14.7 kW kg (based on the total mass of the electrodes), showing the state-of-the-art energy storage ability of the Co(OH) cathode material at device level.
具有优异电子性能和高比表面积的分级纳米结构电极在高性能超级电容器中具有广阔的应用前景。然而，在制备这种结构时，高活性质量负载和均匀结构仍然至关重要。在此，通过水热法将Co(OH)纳米片均匀沉积在镍纳米线阵列（NNA）上，形成NNA@Co(OH)（NNACOH）复合电极。所合成的一维（1D）体系具有类似薰衣草的结构，质量负载高达5.42 mg cm ，比表面积高达74.5 m g 。由于独特的电极结构特性，该电极在1 A g 的电流密度下可提供891.2 F g 的高比电容（对应于5.42 mA cm 时的面积电容为4.83 F cm ）。当电流密度增加到50 A g 时，电容仍可保持721 F g 的高值。此外，该电极表现出优异的循环稳定性，在10 A g 的电流密度下充放电20000次后，电容保持率为89.3%。采用NNACOH作为正极，活性炭（AC）作为负极，组装了一种柔性非对称超级电容器（ASC）。在712 W kg 的功率密度下，它的最大能量密度为23.1 W h kg ，在14.7 kW kg 的最大功率密度下，能量密度为13.5 W h kg （基于电极的总质量），显示了Co(OH)阴极材料在器件层面的先进储能能力。
